Mozilla began automatically blocking the Adobe Flash Player, a web video and animation tool, from running in its Firefox web browser on Tuesday following concerns about Flash's security.

About 16% of people use Firefox to browse the web, the world's third-most popular browser. While cutting Flash out of Firefox was by no means lethal to Adobe, it looks more and more like the market is turning against Flash.

"Following Adobe's advisory for two critical vulnerabilities in Adobe Flash Player 18.0.0.204 [the latest version of Flash] and earlier versions for Windows, Macintosh and Linux, we have disabled Flash by default in Firefox to protect our users from active exploits which are distributing malware," Mozilla director of product management Chad Weiner told Business Insider.